Electrical condenser



Dec. 29, 1936.

A. DEUTSCHMANN ELECTRICAL cotipENsER Filed Feb' hzo, 1935 zgha.

INVENTOR I a za/Qvgz ATTORNEY Patented Dec. 29, 1936 UNITED STATES PATENT OFFICE 2,065,934 ELECTRICAL CONDENSER Arnold Deutschmann, Boston, Mass. Application February 20, 1933, Serial No. 657,654

3 Claims.

The present invention relates to a method and means for manufacturing molded electrical condensers which are adaptable for use either in electrical power circuits, telephone lines or in 5 radio transmission and reception.

One of the objects of the present invention is to construct a condenser which is cheap and at the: same time, durable, and in which the harmful effects of moisture are practically eliminated.

The construction of the condenser according to the present invention also provides a protection for the electrical connectors taken from the electrodes of the condenser. Further than this the inventor has discovered that in paper rolled condensers, with which the invention is chiefly concerned, moisture apparently creeps along the conducting wire into the rolled paper and weakens thereby the condenser. 2 In addition to the fact that moisture usually enters the ordinary wax impregnated condensers at the electrode connections, the irregularities of the ends of the paper and foil provide a considerable surface where moisture can creep in. Moisture also creeps in at these places because of the fine holes formed in the wax by the escaping air between the layers of paper and foil when the condenser is being impregnated.

In protecting condensers of this type, the ap- 30 plicant has found that by remolding wax impregnated condensers in a second means which covers completely the outside of the condenser, that the condenser might be made completely air tight and sealed from harmful effects of the external atmosphere.

In order, however, to accomplish this result, the applicant has employed a coating which has a considerably higher temperature melting point than the wax used for impregnating the condenser. This coating has two properties which make possible the present construction. Firstly the high temperature material used has a low specific heat, lower than the wax used in the condenser impregnation, and secondly it contracts very little in the manner that it is cooled. As a result the condenser'can be molded and the same characteristics assured for the condenser that it had before the molding process.

The applicant has further discovered that further protection may be obtained for the condenser by applying a rubber coating by a clipping processallowing the coat to extend upward over the surface of the metallic conductor.

Further advantages and objects of the present invention will be understood upon consideration of the description given below in connection with the drawing in which:

Figure 1 shows a top plan view of the mold with the condensers in place.

Figure 2 shows a side view partly broken away. Figure 3 shows a detail of one element with a part broken away.

Figure 4 shows a further detail. Figure 5 shows a modification. Figure 6 shows a detail of the molding device, and

Figure '7, a detail of the method of inserting the conductor into the condenser.

The mold as shown in Figures 1 and 2 comprises a base I with partitions 2, 2, 2, etc., and removable side elements 3 held by spring elements 20, 2| adapted to fit the mold as indicated in Figure 1. The side elements have slots 4, 4, and the condenser I is placed in each compartment with the wires 5 and 6 extending through the slots. These wires connect to the opposite electrodes of the condenser. Within the metal mold is a rubber mold as indicated in Figure 6, each pan or cup like element ll fitting in between two partitions. In Figure 2 the side view of the mold is shown with a portionbroken away showing the condenser and the externally molded cover 8. The metal mold indicated in Figure 2 by 9 may hold a celluloid mold 9 or form as is shown in Figure 3, but preferably the entire mold as indicated in Figure 6 is lined with a series of rubber pans which are joined together at their top edgesso as to form one piece, which can be removed from the mold simply by raising and pulling the end flap l2.

The rubber mold shown in Figure 6 lies in the metal mold as indicated in Figures 1 and 2. In

the process of making the condenser, the condenser is first rolled in the usual manner and then impregnated with the ordinary low melting point wax or paraffin. For this purpose ordinary impregnating paraflin or wax of the type of Hallowax may be used. When the condensers are impregnated they are placed in the molds as indicated in Figure 1 inside, of the rubber mold lining the walls of the metal mold. The high melting point compound which may be a composition of 50% gum rosin and 50% silica has a melting point of around 290 F. is then poured over the condensers and is allowed to cool normally in air. This material used has a comparatively low specific heat and one which .upon ordinary cooling does not contract.

The rubber mold serves two purposes, one preventing too rapid cooling and. therefore excescondenser.

sive contraction and at the same time allowing the condenser to be taken from the mold without sticking. The rubber mold also provides a fine finish for the cover and no further polishing or finishing is necessary.

" The rubber mold should be of pure gum rubber as otherwise the heat applied tends to dis- Y integrate the rubber.

In Figure 4 there is shown a part section through the condenser showing the ordinary position that the condenser takes in the melting compound. The condenser here is indicated as wound of paper l3, l3, with layers of foil l4, M in between.

It will be noted in Figure 1, that leads 5 and 6 are held fixed by the harder molded compound and that there is no. strain onthe internal'connection in the condenser from the leads coming out of the condenser. In Figure 5 the condenser is further illustrated as covered with a rubber dipped coating l5 which covers the conducting leads for a very short distance Hi from the condenser. In place of this method of coating the condenser and covering the leads a self contracting cellulose cap may be used which when placed over the condenser contracts and snugly covers the condenser and leads. In Figure 7 is indicated a novel'means for inserting the electrode in the Here the connecting wire 5 is flattened at the end in a fiat strip like piece of metal ll.

be inserted within the condenser and forms a This in winding the condenser may good connection, thus eliminating the necessity of soldering the lead to a strip placed in the condenser or to the foil edges for connecting the condenser as previously practiced.

Having now described my invention, I claim: 1. A method of molding condensers which comprises placing the condenser in a rubber mold within a metal frame pouring the molding compound at a high temperature over the condenser in the rubber mold, allowing it to cool, removing the rubber mold, and removing then the molded condensers from the rubber mold.

2. A method of molding condensers which comprises placing a wax impregnated condenser in a rubber mold, pouring in the mold over the condenser a molding compound having a higher temperature melting point than the wax impregnating the condenser allowing it to cool normally, and removing the molded condenser when cool from therubber mold,

3. A method of molding condensers employing a rubber mold and a composite external frame which consists in placing an impregnated but uncovered condenser in said rubber mold, pouring a high-temperature melting compound into said mold and allowing it to flow around the said condenser and on top thereof, allowing the compound to cool in the mold'whereby rapid radiation is prevented :and removing the condenser after the compound has substantially solidified, first removing the composite external frame.

- ARNOLD DEUTSCHMANN. 

